JP5303157B2 - Light emitting element - Google Patents

Abstract

It is an object to provide a light-emitting element with high luminous efficiency by using a hole transporting substance with a sufficiently high T1 level. Further, it is another object to provide a light-emitting device and an electronic appliance with low power consumption by using a hole transporting substance with a sufficiently high T1 level. The present invention provides a light-emitting element which has a first layer containing a spiro-9,9′-bifluorene derivative in which one amino group is combined and a second layer containing a phosphorescent compound between an anode and a cathode.

Description

The present invention relates to a light-emitting element using a spirofluorene derivative. The present invention also relates to a light emitting device using the light emitting element. The present invention also relates to an electronic apparatus using the light emitting device.

An organic compound is excited by absorbing light. And by passing through this excited state, various reactions (photochemical reactions) may occur or light emission (luminescence) may occur, and various applications have been made.

As an example of the photochemical reaction, there is a reaction (oxygen addition) of singlet oxygen with an unsaturated organic molecule (see, for example, Non-Patent Document 1). Since oxygen molecules have a triplet ground state, singlet oxygen (singlet oxygen) is not generated by direct photoexcitation. However, singlet oxygen is generated in the presence of other triplet excited molecules, which can lead to an oxygen addition reaction. At this time, a compound capable of forming a triplet excited molecule is called a photosensitizer.

Thus, in order to generate singlet oxygen, a photosensitizer capable of forming a triplet excited state by photoexcitation is necessary. However, since a normal organic compound has a singlet ground state, photoexcitation to the triplet excited state is a forbidden transition, and triplet excited molecules are hardly generated. Therefore, as such a photosensitizer, a compound that easily causes an intersystem crossing from a singlet excited state to a triplet excited state (or a compound that allows forbidden transition to cause photoexcitation directly into a triplet excited state). Is required. In other words, such a compound can be used as a photosensitizer and can be said to be useful.

Also, such compounds often emit phosphorescence. Phosphorescence is light emission caused by transitions between energies of different multiplicity. In ordinary organic compounds, light emission occurs when returning from a triplet excited state to a singlet ground state (as opposed to singlet). The light emitted when returning from the excited state to the singlet ground state is called fluorescence.) As an application field of a compound capable of emitting phosphorescence, that is, a compound capable of converting a triplet excited state into light emission (hereinafter referred to as a phosphorescent compound), a light-emitting element using a light-emitting substance of an organic compound can be given.

The structure of this light-emitting element is a simple structure in which a light-emitting layer containing an organic compound, which is a light-emitting substance, is provided between the electrodes. From the characteristics such as thin and light, high-speed response, and direct current low-voltage drive, It attracts attention as a flat panel display element. In addition, a display using this light-emitting element is characterized by excellent contrast and image quality and a wide viewing angle.

The light emitting mechanism of a light emitting element using an organic compound as a light emitting substance is a carrier injection type. That is, by applying a voltage with the light emitting layer sandwiched between the electrodes, electrons and holes injected from the electrodes are recombined and the light emitting substance becomes excited, and emits light when the excited state returns to the ground state. And as a kind of excited state, a singlet excited state (S ^* ) and a triplet excited state (T ^* ) are possible like the case of the optical excitation mentioned above. Further, the statistical generation ratio of the light emitting element is considered to be S ^* : T ^* = 1: 3.

A compound that converts a singlet excited state into light emission (hereinafter referred to as a fluorescent compound) does not emit light (phosphorescence) from the triplet excited state at room temperature, and only emits light (fluorescence) from the singlet excited state. Observed. Therefore, the theoretical limit of the internal quantum efficiency (ratio of photons generated with respect to injected carriers) in a light emitting device using a fluorescent compound is 25% on the basis that S ^* : T ^* = 1: 3. It is said that.

On the other hand, if the phosphorescent compound described above is used, the internal quantum efficiency can theoretically be as high as 75 to 100%. That is, the light emission efficiency is 3 to 4 times that of the fluorescent compound. For these reasons, in order to realize a highly efficient light-emitting element, a light-emitting element using a phosphorescent compound has been actively developed in recent years (see, for example, Non-Patent Documents 1 and 2).

Tetsuo Tetsui, 8 others, Japanese Journal of Applied Physics, vol. 38, L1502-L1504 (1999) Chihaya Adachi, 5 others, Applied Physics Letters, Vol. 78, no. 11, 1622-1624 (2001)

An organometallic complex as disclosed in Non-Patent Document 1 or 2 is a phosphorescent compound and easily emits light (phosphorescence) from a triplet excited state, and thus has high emission efficiency when applied to a light-emitting element. A light emitting element is expected to be obtained. In order to cause such a light-emitting element to emit light with high efficiency, a substance having a sufficiently high triplet excitation energy level (T ₁ level) is applied to a hole-transporting layer in contact with a light-emitting layer containing a phosphorescent compound. Is needed. However, there are very few reports of substances that can be applied to light-emitting elements while having a sufficiently high T ₁ level and sufficient hole transportability. The triplet excitation energy is an energy difference between the ground state and the triplet excited state.

In view of the above, an object of the present invention is to provide a light-emitting element with high emission efficiency using a hole-transporting substance having a sufficiently high T ₁ level.

It is another object of the present invention to provide a light-emitting device and an electronic device with reduced power consumption by using the light-emitting element of the present invention.

As a result of extensive studies, the present inventor has found that a spiro-9,9′-bifluorene derivative bonded with one amino group has a high T ₁ level and a hole transport property. And it discovered that a light emitting element with high luminous efficiency could be obtained by applying a light emitting layer containing a phosphorescent compound and a layer containing the spiro-9,9′-bifluorene derivative to the light emitting element.

Therefore, the structure of the present invention includes a first layer containing a spiro-9,9′-bifluorene derivative having one amino group bonded between an anode and a cathode, a second layer containing a phosphorescent compound, It is a light emitting element which has.

Of the above-mentioned spiro-9,9′-bifluorene derivatives, those in which one amino group is bonded to the ₂ -position have a sufficiently high T ₁ level of the spiro-9,9′-bifluorene derivatives, Thermal properties are also sufficiently high. Therefore, the structure of the present invention includes a first layer containing a spiro-9,9′-bifluorene derivative in which one amino group is bonded to the 2-position between the anode and the cathode, and a second layer containing a phosphorescent compound. A light emitting element having the above layer is preferable.

In the above light-emitting element, more specifically, the amino group is substituted with a substituted or unsubstituted aryl group, or the amino group is substituted with a substituted or unsubstituted heterocyclic group. The light emitting element is preferable.

In addition, since the amino group has a hole transport property, in the above light-emitting element, the light-emitting element in which the first layer is located on the anode side with respect to the second layer is preferable.

Further, since the T ₁ level of the first layer is high, in the above light-emitting element, the light-emitting element in which the first layer and the second layer are adjacent to each other can achieve particularly high light emission efficiency. Therefore, in the above light-emitting element, a light-emitting element in which the first layer and the second layer are adjacent to each other is preferable.

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (1) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(In the formula, R ¹ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ² and R ³ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ⁴ represents an aryl group having 6 to 15 carbon atoms, R ⁵ and R ^{6 each} represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, Each may be the same or different.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (2) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ⁷ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ⁸ and R ⁹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. R ¹⁰ represents any of an aryl group having 6 to 15 carbon atoms, and R ¹¹ and R ¹² are any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms. Each may be the same or different.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (3) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ¹³ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ¹⁴ and R ¹⁵ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. R ¹⁶ represents an aryl group having 6 to 15 carbon atoms, R ¹⁷ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ¹⁸ represents It represents either an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 15 carbon atoms.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (4) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ¹⁹ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ²⁰ and R ²¹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. R ²² represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ²³ and R ²⁴ are hydrogen, an alkyl group having 1 to 4 carbon atoms, or It represents any of aryl groups having 6 to 15 carbon atoms, and may be the same or different.

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (5) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ²⁵ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ²⁶ and R ²⁷ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. R ²⁸ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ²⁹ and R ³⁰ are hydrogen, an alkyl group having 1 to 4 carbon atoms, or It represents any of aryl groups having 6 to 15 carbon atoms, and may be the same or different.

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (6) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ³¹ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ³² and R ³³ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. R ³⁴ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ³⁵ represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or 6 carbon atoms. Represents one of ˜15 aryl groups, and R ³⁶ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (7) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ³⁷ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ³⁸ and R ³⁹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. May be.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (8) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ⁴⁰ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ⁴¹ and R ⁴² represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. May be.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (9) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ⁴³ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ⁴⁴ and R ⁴⁵ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. May be.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (10) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ⁴⁶ and R ⁴⁷ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (11) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ⁴⁸ and R ⁴⁹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following general formula (12) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

(However, in the formula, R ⁵⁰ and R ⁵¹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different.)

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following structural formula (13) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following structural formula (14) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

In another configuration of the present invention, a first layer containing a spirofluorene derivative represented by the following structural formula (15) and a second layer containing a phosphorescent compound are provided between an anode and a cathode. The light emitting element having is preferable.

In the above light-emitting element, the light-emitting element in which the first layer is located on the anode side with respect to the second layer is preferable.

In the above light-emitting element, a light-emitting element in which the first layer and the second layer are adjacent to each other is preferable.

In addition, since the light-emitting element of the present invention thus obtained can achieve high light emission efficiency, a light-emitting device (an image display device or a light-emitting device) using the light-emitting element as a light-emitting element can also realize low power consumption. Therefore, the present invention includes a light-emitting device using the light-emitting element of the present invention. In addition, electronic devices using the light-emitting device are also included.

The light emitting device of the present invention includes the light emitting element of the present invention and control means for controlling light emission of the light emitting element. Note that the light-emitting device in this specification includes an image display device or a light-emitting device using a light-emitting element. Further, the light emitting device of the present invention includes a module in which a connector, for example, an anisotropic conductive film or a TAB (Tape Automated Bonding) tape such as TCP (Tape Carrier Package) tape is connected to a substrate on which a light emitting element is formed, It includes a module in which a printed wiring board is provided, and a module in which an IC (integrated circuit) is directly mounted on a substrate on which a light emitting element is formed by a COG (Chip On Glass) method.

In addition, an electronic device of the present invention includes a display unit, and the display unit includes the above-described light emitting element and a control unit that controls light emission of the light emitting element.

The light-emitting element of the present invention uses a spiro-9,9′-bifluorene derivative having a sufficient hole transporting property and a sufficiently high T ₁ level, and thus has high luminous efficiency and reduced power consumption. A light emitting element can be obtained.

In addition, by using the light-emitting element of the present invention, a light-emitting device and an electronic device with high light emission efficiency and low power consumption can be obtained.

Below, this invention is demonstrated in detail using drawing. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

(Embodiment 1)
In the first embodiment, the concept of the light-emitting element of the present invention will be described.

In recent years, the present inventors have focused on phosphorescent compounds for improving the performance of light-emitting elements, and have studied light-emitting elements using a wide variety of phosphorescent compounds. As one of the results, a phosphorescent compound that has been reported so far can be obtained by using a spiro-9,9′-bifluorene derivative to which one amino group is bonded in a light emitting device using the phosphorescent compound. It was found that very high-efficiency light emission can be obtained compared to the light-emitting element used.

Here, according to the evaluation of physical properties by the present inventors, it was found that the spiro-9,9′-bifluorene derivative has a high T ₁ level. That is, it has been found that the triplet excitation energy does not easily transfer from another layer to the layer using the spiro-9,9′-bifluorene derivative. Therefore, even if the phosphorescent color from the light emitting layer is a light emitting color having a large light emitting energy such as blue to green, there is little fear that the excitation energy from the light emitting layer moves.

Furthermore, the spiro-9,9'-bifluorene derivative has sufficient hole transportability and is also suitable as a material for the hole transport layer. Further, it was found that the spiro-9,9'-bifluorene derivative has a relatively high lowest unoccupied molecular orbital (LUMO) level. That is, it is possible to prevent electrons from penetrating from one layer to the other in the layer using the spiro-9,9'-bifluorene derivative.

The spiro-9,9'-bifluorene derivative has been found to be a material having a high glass transition temperature (Tg) and high heat resistance. Therefore, a light-emitting element with high heat resistance can be obtained.

The present inventors have found that the high T ₁ level, hole transporting property, electron blocking property, and high heat resistance characteristic of this spiro-9,9′-bifluorene derivative are many when producing a light-emitting element. It was found from the experimental results that there is a merit.

When a light-emitting element using a phosphorescent compound for a light-emitting layer is formed, when a hole transport layer is formed using a general hole-transporting material, the hole-transporting material is compared with a phosphorescent compound or its host material. Since the T ₁ level is low, the triplet excitation energy easily moves to the hole transport layer adjacent to the light emitting layer. However, since the spiro-9,9′-bifluorene derivative having a sufficient hole transporting property has a high T ₁ level, transfer of triplet excitation energy from the light-emitting layer hardly occurs. Therefore, a light-emitting element with high light emission efficiency and color purity can be obtained.

In addition, since the spiro-9,9′-bifluorene derivative having a high LUMO level is used for the hole transport layer adjacent to the light emitting layer, it is possible to prevent electrons from penetrating from the light emitting layer to other layers. And holes can be efficiently recombined in the light-emitting layer, and a light-emitting element with high emission efficiency can be obtained.

(Embodiment 2)
In Embodiment Mode 2, the structure of the light-emitting element of the present invention will be described with reference to FIG.

FIG. 1 illustrates a light-emitting element having a layer 120 containing an organic compound between a first electrode 101 and a second electrode 104. The layer 120 containing an organic compound includes a first layer 102 containing a spiro-9,9'-bifluorene derivative and a second layer 103 containing a phosphorescent compound.

Here, the structure of the second layer 103 containing a phosphorescent compound is a layer formed by using a substance having triplet excitation energy larger than that of the phosphorescent compound as a host and dispersing the phosphorescent compound as a guest. preferable. By dispersing the phosphorescent compound that is the emission center substance, it is possible to prevent light emitted from the phosphorescent compound from being quenched due to the concentration.

There is no limitation on the phosphorescent compound, but bis [2- (3,5-bis (trifluoromethyl) phenyl) pyridinato-N, C ^{2 ′} ] iridium (III) picolinate (abbreviation: Ir (CF ₃ ppy) ₂ ( pic)), bis [2- (4,6-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (III) acetylacetonate (abbreviation: FIr (acac)), bis [2- (4,6-difluoro Phenyl) pyridinato-N, C ^{2 ′} ] iridium (III) picolinate (FIr (pic)), bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (III) tetra (III) 1-pyrazolyl) borate (abbreviation: FIr ₆ ), tris (2-phenylpyridinato-N, C ^{2 ′} ) iridium (abbreviation: Ir (ppy) ₃ ), (Acetylacetonato) bis [2-phenylpyridinato] iridium (III) (abbreviation: Ir (ppy) ₂ (acac)), bis (1,2-diphenyl-1H-benzimidazolato) iridium (III) acetyl Acetonate (abbreviation: Ir (pbi) ₂ (acac)), bis (benzo [h] quinolinato) iridium (III) acetylacetonate (abbreviation: Ir (bzq) ₂ (acac)), bis (2,4-diphenyl) -1,3-oxazolate-N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: Ir (dpo) ₂ (acac)), bis [2- (4′-perfluorophenylphenyl) pyridinato] iridium ( III) acetylacetonate _{(abbreviation: Ir (p-PF-ph} ) 2 (acac)), bis (2-phenyl Nzochiazorato -N, C ^{2 ')} iridium (III) acetylacetonate _{(abbreviation: Ir (bt) 2 (acac} )), tris (2-phenylquinolinato -N, C ^2') iridium (III) (abbreviation: Ir (Pq) ₃ ), bis (2-phenylquinolinato-N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: Ir (pq) ₂ (acac)), bis [2- (2′-benzo [ 4,5-α] thienyl) pyridinato-N, C ^{3 ′} ] iridium (III) acetylacetonate (abbreviation: Ir (btp) ₂ (acac)), bis (1-phenylisoquinolinato-N, C ^{2 ′} ) iridium (III) acetylacetonate _{(abbreviation: Ir (piq) 2 (acac} )), tris (1-phenylisoquinolinato--N, C ^{2 ')} iridium (III (Abbreviation: Ir _(piq) 3), (acetylacetonato) bis [2,3-bis (4-fluorophenyl) quinoxalinato] iridium (III) _{(abbreviation: Ir (Fdpq) 2 (acac} )), 2,3 , 7, 8, 12, 13, 17, 18-octaethyl-21H, 23H-porphyrin platinum (II) (abbreviation: PtOEP). In addition, tris (acetylacetonato) (monophenanthroline) terbium (III) (abbreviation: Tb (acac) ₃ (Phen)), tris (1,3-diphenyl-1,3-propanedionate) (monophenanthroline) europium (III) (abbreviation: Eu (DBM) ₃ (Phen)), tris [1- (2-thenoyl) -3,3,3-trifluoroacetonato] (monophenanthroline) europium (III) (abbreviation: Eu ( A rare earth metal complex such as TTA) ₃ (Phen)) emits light from a rare earth metal ion (electron transition between different multiplicity), and thus can be used as the phosphorescent compound of the present invention. In that sense, a phosphor of an inorganic compound such as a metal oxide to which a rare earth is added can also be used. Note that since the first layer 102 includes a spiro-9,9′-bifluorene derivative, a phosphorescent compound having green or blue emission or a phosphorescent compound having an emission spectrum peak from 440 nm to 540 nm is used as the second layer 102. Even if it is used for the layer 103, energy transfer can be suppressed and high luminous efficiency can be realized. Examples of such phosphorescent compounds include Ir (CF ₃ ppy) ₂ (pic), FIr (acac), FIr (pic), FIr ₆ , Ir (ppy) ₃ , Ir (ppy) ₂ (acac), Ir (Pbi) ₂ (acac) and the like.

There is no particular limitation on a substance (that is, a host) used for bringing the phosphorescent compound into a dispersed state, but there is no limitation on 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB). In addition to such compounds having an arylamine skeleton, 4,4′-di (N-carbazolyl) biphenyl (abbreviation: CBP), 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine (abbreviation: Carbazole derivatives such as TCTA), bis [2- (2-hydroxyphenyl) pyridinato] zinc (abbreviation: Znpp ₂ ), bis [2- (2-hydroxyphenyl) benzoxazolate] zinc (abbreviation: Zn (PBO) ) _2), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (abbreviation: BAlq), tris (8-quinolinolato) Al Bromide (abbreviation: Alq ₃₎ metal complexes, and the like are preferable. Alternatively, a high molecular compound may be used as a substance used for bringing the phosphorescent compound into a dispersed state. In this case, the second layer 103 can be formed by applying a solution obtained by dissolving the phosphorescent compound and the polymer compound in an appropriate solvent using a wet method such as an inkjet method or a spin coating method. it can. As the solvent, for example, lower alcohol such as methanol, ethanol, propanol, butanol, sec butanol, tetrahydrofuran (THF), acetonitrile, dichloromethane, dichloroethane, toluene, xylene, or a mixed solvent thereof can be used. It is not limited to. Examples of the polymer compound include poly (N-vinylcarbazole) (abbreviation: PVK), poly (4-vinyltriphenylamine) (abbreviation: PVTPA), and poly [N- (4- {N ′-[4 -(4-Diphenylamino) phenyl] phenyl-N′-phenylamino} phenyl) methacrylamide] (abbreviation: PTPDMA) poly [N, N′-bis (4-butylphenyl) -N, N′-bis (phenyl) ) Benzidine] (abbreviation: Poly-TPD) and the like can be used. Poly [(9,9-dihexylfluorene-2,7-diyl) -co- (pyridine-3,5-diyl)] (abbreviation: PF-Py), poly [(9,9-dioctylfluorene-2) , 7-diyl) -co- (2,2′-bipyridine-6,6′-diyl)] (abbreviation: PF-BPy) can also be used.

Note that the second layer 103 can be formed using, for example, a sputtering method, an evaporation method, or the like, but can also be formed using a wet method such as an inkjet method or a spin coating method.

Here, the first layer 102 containing a spiro-9,9'-bifluorene derivative is formed adjacent to the second layer 103. A spiro-9,9'-bifluorene derivative used for the first layer 102 will be described.

Of the spiro-9,9′-bifluorene derivatives used for the first layer 102, one having an amino group bonded to the ₂ -position has a sufficient T ₁ level of the spiro-9,9′-bifluorene derivative. The thermophysical properties are sufficiently high.

In the above spiro-9,9′-bifluorene derivative, more specifically, the amino group is substituted with a substituted or unsubstituted aryl group, or the amino group is substituted or unsubstituted. Substituted with a heterocyclic group.

A spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (1).

In the formula, R ¹ represents any one of hydrogen and an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ¹ is particularly preferably hydrogen or a tertbutyl group.

In the formula, R ² and R ³ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ² and R ³ are particularly preferably hydrogen or a tertbutyl group. R ² and R ³ may be the same or different.

In the formula, R ⁴ represents an aryl group having 6 to 15 carbon atoms. Examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, 9,9-dimethylfluoren-2-yl group, and naphthyl group. Etc. In order to make the spiro-9,9′-bifluorene derivative represented by the general formula (1) a compound having a larger energy gap, R ⁴ is a condensed ring system among aryl groups having 6 to 15 carbon atoms. It is preferable that it is group which does not contain skeleton of. The aryl group having 6 to 15 carbon atoms may have a substituent, and examples of the substituent include an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, and 9,9-dimethylfluoren-2-yl group. And naphthyl group. R ⁴ is particularly preferably an unsubstituted phenyl group.

Wherein ^R 5, ^{R 6} represents hydrogen, or an aryl group an alkyl group or a C6-15 having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Examples of the aryl group include a phenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a fluoren-2-yl group, a 9,9-dimethylfluoren-2-yl group, and a naphthyl group. As R ⁵ and R ⁶ , hydrogen is particularly preferable. Note that R ⁵ and R ⁶ may be the same or different, and may or may not have a substituent.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (2).

In the formula, R ⁷ represents any one of hydrogen and an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁷ is particularly preferably either hydrogen or a tertbutyl group.

In formula, R < ⁸ >, R < ⁹ > represents either hydrogen or a C1-C4 alkyl group. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁸ and R ⁹ are particularly preferably hydrogen or a tertbutyl group. Note that R ⁸ and R ⁹ may be the same or different.

In the formula, R ¹⁰ represents an aryl group having 6 to 15 carbon atoms. Examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, 9,9-dimethylfluoren-2-yl group, and naphthyl group. Etc. In order to make the spiro-9,9′-bifluorene derivative represented by the general formula (2) a compound having a larger energy gap, R ¹⁰ is preferably a group not containing a skeleton of a condensed ring system. . The aryl group having 6 to 15 carbon atoms may have a substituent, and examples of the substituent include an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, and 9,9-dimethylfluoren-2-yl group. And naphthyl group. R ¹⁰ is particularly preferably an unsubstituted phenyl group.

In the formula, R ¹¹ and R ^{12 each} represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Examples of the aryl group include a phenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a fluoren-2-yl group, a 9,9-dimethylfluoren-2-yl group, and a naphthyl group. As R ¹¹ and R ¹² , hydrogen is particularly preferable. Note that R ¹¹ and R ¹² may be the same or different, and may or may not have a substituent.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (3).

In the formula, R ¹³ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ¹³ is particularly preferably either hydrogen or a tertbutyl group.

In formula, R <^14> , R < ¹⁵ > represents either hydrogen or a C1-C4 alkyl group. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ¹⁴ and R ¹⁵ are particularly preferably hydrogen or a tertbutyl group. Note that R ¹⁴ and R ¹⁵ may be the same or different.

In the formula, R ¹⁶ represents an aryl group having 6 to 15 carbon atoms. Examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, 9,9-dimethylfluoren-2-yl group, and naphthyl group. Etc. In order to make the spiro-9,9′-bifluorene derivative represented by the general formula (3) into a compound having a larger energy gap, R ¹⁶ is preferably a group not containing a skeleton of a condensed ring system. . The aryl group having 6 to 15 carbon atoms may have a substituent, and examples of the substituent include an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, and 9,9-dimethylfluoren-2-yl group. And naphthyl group. R ¹⁶ is particularly preferably an unsubstituted phenyl group.

In the formula, R ¹⁷ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Examples of the aryl group include a phenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a fluoren-2-yl group, a 9,9-dimethylfluoren-2-yl group, and a naphthyl group. R ¹⁷ is particularly preferably hydrogen. R ¹⁷ may or may not have a substituent.

In the formula, R ¹⁸ represents either an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Examples of the aryl group include a phenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a fluoren-2-yl group, a 9,9-dimethylfluoren-2-yl group, and a naphthyl group. In order to make the spiro-9,9′-bifluorene derivative represented by the general formula (5) a compound having a larger energy gap, R ¹⁸ is an alkyl group having 1 to 4 carbon atoms or 6 carbon atoms. Among the ˜15 aryl groups, a group not containing a skeleton of a condensed ring system is preferable. The aryl group having 6 to 15 carbon atoms may have a substituent, and examples of the substituent include an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms as a substituent include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, and 9,9-dimethylfluoren-2-yl group. And naphthyl group. R ¹⁸ is particularly preferably an unsubstituted phenyl group.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (4).

In the formula, R ¹⁹ represents any one of hydrogen and an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ¹⁹ is particularly preferably either hydrogen or a tertbutyl group.

In formula, R <^20> , R < ²¹ > represents either hydrogen or a C1-C4 alkyl group. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ²⁰ and R ²¹ are particularly preferably hydrogen or a tertbutyl group. R ²⁰ and R ²¹ may be the same or different.

In the formula, R ²² represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, and 9,9-dimethylfluorene-2- And yl group and naphthyl group. In order to make the spiro-9,9′-bifluorene derivative represented by the general formula (4) into a compound having a larger energy gap, R ²² may be a group that does not contain a skeleton of a condensed ring system. preferable. R ²² is particularly preferably hydrogen.

In formula, R < ²³ >, R < ²⁴ > represents either hydrogen, a C1-C4 alkyl group, or a C6-C15 aryl group. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Examples of the aryl group include a phenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a fluoren-2-yl group, a 9,9-dimethylfluoren-2-yl group, and a naphthyl group. R ²³ and R ²⁴ are particularly preferably hydrogen. Note that R ²³ and R ²⁴ may be the same or different, and may or may not have a substituent.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (5).

In the formula, R ²⁵ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ²⁵ is particularly preferably either hydrogen or a tertbutyl group.

In the formula, R ²⁶ and R ²⁷ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ²⁶ and R ²⁷ are particularly preferably hydrogen or a tertbutyl group. Note that R ²⁶ and R ²⁷ may be the same or different.

In the formula, R ²⁸ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, and 9,9-dimethylfluoren-2-yl group. And naphthyl group. In order to make the spiro-9,9′-bifluorene derivative represented by the general formula (5) a compound having a larger energy gap, R ²⁸ may be a group that does not contain a skeleton of a condensed ring system. preferable. R ²⁸ is particularly preferably hydrogen.

In the formula, R ²⁹ and R ^{30 each} represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Examples of the aryl group include a phenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a fluoren-2-yl group, a 9,9-dimethylfluoren-2-yl group, and a naphthyl group. As R ²⁹ and R ³⁰ , hydrogen is particularly preferable. Note that R ²⁹ and R ³⁰ may be the same or different, and may or may not have a substituent.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (6).

In the formula, R ³¹ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ³¹ is particularly preferably either hydrogen or a tertbutyl group.

In formula, R ^<32> , R ^<33 > represents either hydrogen or a C1-C4 alkyl group. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ³² and R ³³ are particularly preferably hydrogen or a tertbutyl group. Note that R ³² and R ³³ may be the same or different.

In the formula, R ³⁴ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, fluoren-2-yl group, and 9,9-dimethylfluoren-2-yl group. And naphthyl group. In order to make the spiro-9,9′-bifluorene derivative represented by the general formula (6) a compound having a larger energy gap, R ³⁴ may be a group that does not contain a skeleton of a condensed ring system. preferable. R ³⁴ is particularly preferably hydrogen.

In the formula, R ³⁵ represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. Examples of the aryl group include a phenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a fluoren-2-yl group, a 9,9-dimethylfluoren-2-yl group, and a naphthyl group. R ³⁵ is particularly preferably hydrogen. R ³⁵ may or may not have a substituent.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (7).

In the formula, R ³⁷ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ³⁷ is particularly preferably either hydrogen or a tert butyl group.

In the formula, R ³⁸ and R ³⁹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ³⁸ and R ³⁹ are particularly preferably hydrogen or a tertbutyl group. R ³⁸ and R ³⁹ may be the same or different.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (8).

In the formula, R ⁴⁰ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁴⁰ is particularly preferably either hydrogen or a tertbutyl group.

In the formula, R ⁴¹ and R ⁴² represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁴¹ and R ⁴² are particularly preferably hydrogen or a tertbutyl group. Note that R ⁴¹ and R ⁴² may be the same or different.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (9).

In the formula, R ⁴³ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁴³ is particularly preferably either hydrogen or a tertbutyl group.

Wherein ^{R 44, R 45} represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁴⁴ and R ⁴⁵ are particularly preferably hydrogen or a tertbutyl group. Note that R ⁴⁴ and R ⁴⁵ may be the same or different.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (10).

In the formula, R ⁴⁶ and R ⁴⁷ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁴⁶ and R ⁴⁷ are particularly preferably hydrogen or a tertbutyl group. Note that R ⁴⁶ and R ⁴⁷ may be the same or different.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (11).

In the formula, R ⁴⁸ and R ⁴⁹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁴⁸ and R ⁴⁹ are particularly preferably hydrogen or a tertbutyl group. Note that R ⁴⁸ and R ⁴⁹ may be the same or different.

The spiro-9,9'-bifluorene derivative used for the first layer 102 is represented by the following general formula (12).

Wherein ^{R 50, R 51} represents any of an alkyl group having 1 to 4 carbon hydrogen or carbon. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secbutyl group, and a tertbutyl group. R ⁵⁰ and R ⁵¹ are particularly preferably hydrogen or a tertbutyl group. Note that R ⁵⁰ and R ⁵¹ may be the same or different.

Specific examples of spiro-9,9'-bifluorene derivatives represented by the general formulas (1) to (12) include (13) to (95), for example. In the formula, Me represents a methyl group, Et represents an ethyl group, iPr represents an isopropyl group, Pr represents a propyl group, Bu represents a butyl group, iBu represents an isobutyl group, sBu represents a secbutyl group, and tBu represents a tertbutyl group. Respectively. Note that the spiro-9,9'-bifluorene derivative used in the light-emitting element of the present invention is not limited to these.

Note that the spiro-9,9′-bifluorene derivative described in Embodiment 2 has a sufficiently high T ₁ level and has a sufficient hole-transport property, and thus is preferably used for the hole-transport layer. . The spiro-9,9′-bifluorene derivative described in Embodiment Mode 2 is a material having a high glass transition temperature (Tg) and high heat resistance, and the light-emitting element of the present invention is described above in the first layer. Since a spiro-9,9′-bifluorene derivative is contained, a light-emitting element with high heat resistance can be obtained. In addition, since the spiro-9,9′-bifluorene derivative described in Embodiment 2 has a high T ₁ level, a light-emitting element having high emission efficiency due to less movement of triplet excitation energy from other layers. Is obtained. In addition, since the spiro-9,9′-bifluorene derivative described in Embodiment 2 has a high T ₁ level, light emission with a large emission energy such that the phosphorescence color from the light-emitting layer is blue to green is emitted. It can be suitably used for a light-emitting element exhibiting a color, and a light-emitting element with high luminous efficiency can be obtained. In addition, since the spiro-9,9′-bifluorene derivative described in Embodiment Mode 2 has a high T ₁ level, light emission with high emission energy such that the phosphorescence color from the light-emitting layer is 440 nm to 540 nm is used. It can be suitably used for a light-emitting element exhibiting a color, and a light-emitting element with high luminous efficiency can be obtained.

Further, since the light-emitting element of the present invention has high light emission efficiency, power consumption can be reduced.

By applying a voltage to such a light-emitting element, holes injected from the first electrode 101 side and electrons injected from the second electrode 104 side are recombined in the second layer 103. Then, the phosphorescent compound is brought into an excited state. Then, light is emitted when the phosphorescent compound in the excited state returns to the ground state. Note that in the light-emitting element of Embodiment 2, the first electrode 101 functions as an anode and the second electrode 104 functions as a cathode.

Although there is no particular limitation on the first electrode 101, it is preferable that the first electrode 101 be formed of a material having a high work function when functioning as an anode as in the second embodiment. Specifically, indium tin oxide (ITO), indium tin oxide containing silicon oxide (ITSO), indium oxide containing 2 to 20 wt% zinc oxide (IZO), gold (Au), platinum ( Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or the like can be used. Note that the first electrode 101 can be formed using, for example, a sputtering method, an evaporation method, or the like.

Although there is no particular limitation on the second electrode 104, it is preferable that the second electrode 104 be formed using a substance having a low work function when functioning as a cathode as in the second embodiment. Specifically, in addition to aluminum (Al) and indium (In), alkali metals such as lithium (Li) and cesium (Cs), alkaline earth metals such as magnesium (Mg) and calcium (Ca), erbium (Er Or rare earth metals such as ytterbium (Yb). An alloy such as an aluminum lithium alloy (AlLi) or a magnesium silver alloy (MgAg) can also be used. Note that the second electrode 104 can be formed by, for example, a sputtering method, an evaporation method, or the like.

Note that in order to extract emitted light to the outside, either one or both of the first electrode 101 and the second electrode 104 is an electrode made of a conductive film that transmits visible light such as ITO, or transmits visible light. It is preferable that the electrode is formed with a thickness of several to several tens of nm so as to be able to.

Further, a hole injection layer 111 may be provided between the first electrode 101 and the first layer 102 as shown in FIG. Here, the hole injection layer is a layer having a function of assisting injection of holes from the electrode functioning as an anode into the first layer 102. However, the hole injection layer 111 is not always necessary.

Although there is no particular limitation on the substance constituting the hole injection layer 111, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, ruthenium oxide A metal oxide such as a product can be used. Alternatively, a phthalocyanine compound such as phthalocyanine (abbreviation: H ₂ Pc) or copper phthalocyanine (CuPC) can be used. In addition, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB), 4,4′-bis [N- (3-methylphenyl) -N-phenylamino] Biphenyl (abbreviation: TPD), 4,4′-bis [N- (9,9-dimethylfluoren-2-yl) -N-phenylamino] biphenyl (abbreviation: DFLDPBi), 4,4 ′, 4 ″- Tris (N, N-diphenylamino) triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: m Aromatic amine compounds such as -MTDATA) can also be used. Alternatively, a high molecular compound such as a mixture of poly (ethylenedioxythiophene) and poly (styrenesulfonic acid) (abbreviation: PEDOT / PSS) can be used.

Alternatively, a composite material obtained by mixing an organic compound and an electron acceptor may be used for the hole injection layer 111. Such a composite material is excellent in hole injecting property and hole transporting property because holes are generated in the organic compound by the electron acceptor. In this case, the organic compound is preferably a material excellent in transporting the generated holes, and specifically, the above-described aromatic amine compound or the like can be used. The electron acceptor may be any substance that exhibits an electron accepting property with respect to an organic compound. Specifically, it is preferably a transition metal oxide, for example, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, ruthenium. An oxide etc. are mentioned. A Lewis acid such as iron (III) chloride or aluminum (III) chloride can also be used. Alternatively, an organic compound such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ₄ -TCNQ) can be used.

Note that the hole injection layer 111 may have a multilayer structure in which two or more layers are stacked. Further, two or more kinds of substances may be mixed and formed.

Further, an electron transporting layer 112 may be provided between the second electrode 104 and the second layer 103 as shown in FIG. Here, the electron transport layer is a layer having a function of transporting electrons injected from the second electrode 104 to the second layer 103. In this manner, by providing the electron transport layer 112 and separating the second electrode 104 and the second layer 103, light emission can be prevented from being quenched due to the metal. However, the electron transport layer 112 is not always necessary.

There is no particular limitation on a substance included in the electron-transport layer 112; typically, tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq _3). ), Bis (10-hydroxybenzo [h] quinolinato) beryllium (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (abbreviation: BAlq), bis [2- ( Metal complexes such as 2-hydroxyphenyl) benzoxazolate] zinc (abbreviation: ZnBOX) and bis [2- (2-hydroxyphenyl) benzothiazolate] zinc (abbreviation: Zn (BTZ) ₂ ). 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis [5- (pt-butyl) Phenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 3- (4-t-butylphenyl) -4-phenyl-5- (4-biphenylyl) -1 , 2,4-triazole (abbreviation: TAZ), 3- (4-t-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) -1,2,4-triazole (abbreviation: heteroaromatic compounds such as p-EtTAZ), bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), 4,4′-bis (5-methylbenzoxazol-2-yl) stilbene (abbreviation: BzOs) To use You can. Alternatively, a high molecular compound such as poly (2,5-pyridine-diyl) (abbreviation: PPy) can be used.

Note that the electron transport layer 112 may have a multilayer structure formed by stacking two or more layers. Further, two or more kinds of substances may be mixed and formed.

Further, an electron injection layer 113 may be provided between the second electrode 104 and the electron transport layer 112 as shown in FIG. Here, the electron injection layer is a layer having a function of assisting injection of electrons from the electrode functioning as a cathode into the electron transport layer 112. However, the electron injection layer 113 is not always necessary.

There is no particular limitation on the substance forming the electron injection layer 113, but an alkali metal compound such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), lithium oxide, or alkaline earth is used. Metal compounds can be used. Alternatively, a rare earth metal compound such as erbium fluoride (ErF ₃ ) can be used. In addition, a substance constituting the electron transport layer 112 described above can be used.

Alternatively, a composite material obtained by mixing an organic compound and an electron donor may be used for the electron injection layer 113. Such a composite material is excellent in electron injecting property and electron transporting property because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material excellent in transporting the generated electrons. Specifically, for example, a substance (metal complex, heteroaromatic compound, or the like) constituting the electron transport layer 112 described above is used. Can be used. The electron donor may be any substance that exhibits an electron donating property to the organic compound. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferable, and lithium, cesium, magnesium, calcium, erbium, ytterbium, and the like can be given. Alkali metal oxides and alkaline earth metal oxides are preferable, and lithium oxide, calcium oxide, barium oxide, and the like can be given. A Lewis base such as magnesium oxide can also be used. Alternatively, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can be used.

In the light-emitting element of the present invention described above, the hole injecting layer 111, the first layer 102, the second layer 103, the electron transporting layer 112, and the electron injecting layer 113 are formed by an evaporation method, an inkjet method, or It may be formed by any method such as a coating method. Further, the first electrode 101 or the second electrode 104 may be formed by any method such as a sputtering method, a vapor deposition method, an inkjet method, or a wet method such as a coating method.

(Embodiment 3)
In Embodiment Mode 3, a first layer containing a plurality of spiro-9,9′-bifluorene derivatives and a second layer containing a phosphorescent compound are provided, and each phosphorescence is different in element structure from Embodiment Mode 2. An example of a light-emitting element that emits light from a second layer containing a functional compound is shown. Therefore, light emission in which a plurality of light emissions are mixed can be obtained. In Embodiment Mode 3, a mode of a light-emitting element having a first layer containing a plurality of spiro-9,9′-bifluorene derivatives and a second layer containing a phosphorescent compound will be described with reference to FIGS.

In the light-emitting element in FIG. 2, a layer A 203 containing an organic compound and a layer B 206 containing an organic compound are provided between the first electrode 201 and the second electrode 202. A layer A203 containing an organic compound is provided with a first layer 212 containing a spiro-9,9'-bifluorene derivative and a second layer 213 containing a phosphorescent compound. The layer B206 containing an organic compound is provided with a first layer 215 containing a spiro-9,9'-bifluorene derivative and a second layer 216 containing a phosphorescent compound. Further, an N layer 204 and a P layer 205 are provided as a charge generation layer between the layer A 203 containing an organic compound and the layer B 206 containing an organic compound.

The N layer 204 is a layer that generates electrons, and the P layer 205 is a layer that generates holes. When a voltage is applied so that the potential of the first electrode 201 is higher than the potential of the second electrode 202, the holes injected from the first electrode 201 and the electrons injected from the N layer 204 are phosphorescent. In the second layer 213 containing a luminescent compound, recombination occurs, and the phosphorescent compound contained in the second layer 213 containing a luminescent compound emits light. Further, electrons injected from the second electrode 202 and holes injected from the P layer 205 are recombined in the second layer 216 containing a phosphorescent compound, and the second layer 216 containing the phosphorescent compound is combined. The contained phosphorescent compound emits light.

Since the N layer 204 is a layer that generates electrons, the N layer 204 may be formed using a composite material obtained by mixing the organic compound and the electron donor described in Embodiment 2 above. With such a structure, electrons can be injected into the second layer 213 side containing a phosphorescent compound.

Since the P layer 205 is a layer that generates holes, it may be formed using a composite material obtained by mixing the organic compound and the electron acceptor described in Embodiment 2 above. With such a structure, holes can be injected into the second layer 216 side containing a phosphorescent compound. For the P layer 205, a metal oxide having excellent hole injection properties such as molybdenum oxide, vanadium oxide, ITO, and ITSO can also be used.

Further, a layer may be formed between the N layer 204 and the P layer 205 to such an extent that light can pass through a metal oxide such as molybdenum oxide or ITSO, or a metal such as aluminum or silver.

The layer A203 containing an organic compound and the layer B206 containing an organic compound may have a structure similar to that of the layer 120 containing an organic compound described in Embodiment 2. For example, as shown in FIG. 2, in the layer A containing an organic compound, a hole injection layer 211 is provided between the first electrode 201 and the first layer 212, and the second layer 213 and the N layer 204 are provided. An electron transport layer 214 is provided between the two. In the layer B containing an organic compound, an electron transport layer 217 and an electron injection layer 218 are provided between the second electrode 202 and the second layer 216.

In Embodiment 3, a light-emitting element provided with a layer containing two organic compounds as shown in FIG. 2 is described, but the number of layers containing an organic compound is limited to two. Instead, for example, there may be three. Then, light emission from the second layer containing each phosphorescent compound may be mixed.

Alternatively, Embodiment Mode 3 describes a light-emitting element in which two organic compound layers are provided as shown in FIG. 2 and each layer includes a phosphorescent compound. For example, two layers including an organic compound are provided. Provided, one of the layers containing two organic compounds may have a structure different from that of the present invention. As a different configuration of the present invention, for example, a configuration in which a fluorescent compound is applied instead of the phosphorescent compound of the second layer containing the phosphorescent compound can be given. The light emission from the second layer containing each phosphorescent compound and the layer containing the fluorescent compound may be mixed.

(Embodiment 4)
In Embodiment Mode 4, a light-emitting device manufactured using the light-emitting element of the present invention will be described.

In Embodiment Mode 4, a light-emitting device manufactured using the light-emitting element of the present invention will be described with reference to FIGS. 3A is a top view illustrating the light-emitting device, and FIG. 3B is a cross-sectional view taken along line A-A ′ in FIG. 3A. Reference numeral 401 indicated by a dotted line is a drive circuit portion (source side drive circuit), 402 is a pixel portion, and 403 is a drive circuit portion (gate side drive circuit). Reference numeral 404 denotes a sealing substrate, and reference numeral 405 denotes a sealing material. An inner side surrounded by the sealing material 405 is a space 407.

Note that the routing wiring 408 is a wiring for transmitting a signal input to the source side driving circuit 401 and the gate side driving circuit 403, and a video signal, a clock signal, an FPC (flexible printed circuit) 409 serving as an external input terminal, Receives start signal, reset signal, etc. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light-emitting device in this specification includes not only a light-emitting device body but also a state in which an FPC or a PWB is attached thereto.

Next, a cross-sectional structure will be described with reference to FIG. A driver circuit portion and a pixel portion are formed over the substrate 410. Here, a source side driver circuit 401 which is a driver circuit portion and one pixel in the pixel portion 402 are illustrated.

Note that the source side driver circuit 401 is formed with a CMOS circuit in which an n-channel TFT 423 and a p-channel TFT 424 are combined. The driver circuit may be formed of a CMOS circuit, a PMOS circuit, or an NMOS circuit. In the fourth embodiment, a driver integrated type in which a drive circuit is formed on a substrate is shown, but this is not always necessary, and the driver circuit can be formed outside the substrate.

The pixel portion 402 is formed by a plurality of pixels including a switching TFT 411, a current control TFT 412, and a first electrode 413 electrically connected to the drain thereof. Note that an insulator 414 is formed so as to cover an end portion of the first electrode 413. Here, a positive photosensitive acrylic resin film is used.

In order to improve the coverage, a curved surface having a curvature is formed at the upper end portion or the lower end portion of the insulator 414. For example, in the case where positive photosensitive acrylic is used as the material of the insulator 414, it is preferable that only the upper end portion of the insulator 414 has a curved surface having a curvature radius (0.2 μm to 3 μm). As the insulator 414, either a negative type that becomes insoluble in an etchant by photosensitive light or a positive type that becomes soluble in an etchant by light can be used.

Over the first electrode 413, a layer 416 containing an organic compound and a second electrode 417 are formed. Here, as a material used for the first electrode 413 functioning as an anode, a material having a high work function is preferably used. For example, an ITO (indium tin oxide) film or a single layer such as an indium tin oxide film containing silicon, an indium zinc oxide (IZO) film, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film In addition to the film, a stack of titanium nitride and a film containing aluminum as a main component, a three-layer structure of a titanium nitride film, a film containing aluminum as a main component, and a titanium nitride film can be used. Note that when a stacked structure is used, resistance as a wiring is low, a favorable ohmic contact can be formed, and a function as an anode can be obtained.

The layer 416 containing an organic compound is formed by various methods such as an evaporation method using an evaporation mask, an ink-jet method, or a spin coating method. For the layer 416 containing an organic compound, the spiro-9,9′-bifluorene derivative and the phosphorescent compound described in Embodiment 2 are used as a part thereof, and other materials that can be used in combination are: It may be a low molecular material, a medium molecular material (including oligomers and dendrimers) having intermediate properties between a low molecule and a polymer, or a high molecular material. In addition, as a material used for a layer containing an organic compound, an organic compound is usually used in a single layer or a stacked layer. However, in the present invention, a configuration in which an inorganic compound is used for part of a film made of an organic compound is also included. I will do it.

Further, as a material used for the second electrode 417 formed over the layer 416 containing an organic compound, a material having a low work function (Al, Ag, Li, Ca, or an alloy or compound thereof, MgAg, MgIn, AlLi, or the like) , CaF ₂ , calcium nitride, or calcium fluoride) is preferably used. Note that in the case where light generated in the layer 416 containing an organic compound is transmitted through the second electrode 417 functioning as a cathode, a thin metal film and a transparent conductive film (ITO) are used as the second electrode 417. A stack of (indium tin oxide alloy), indium oxide zinc oxide alloy (In ₂ O ₃ —ZnO), zinc oxide (ZnO), or the like is preferably used.

Further, the light-emitting element 418 is provided in the space 407 surrounded by the substrate 410, the sealing substrate 404, and the sealing material 405 by bonding the sealing substrate 404 to the substrate 410 with the sealing material 405. Note that the space 407 includes a structure filled with a sealing material 405 in addition to a case where the space 407 is filled with an inert gas (such as nitrogen or argon).

Note that an epoxy-based resin is preferably used for the sealant 405. Moreover, it is desirable that these materials are materials that do not transmit moisture and oxygen as much as possible. In addition to a glass substrate and a quartz substrate, a plastic substrate made of FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic, or the like can be used as a material used for the sealing substrate 404.

As described above, a light-emitting device manufactured using the light-emitting element of the present invention can be obtained.

Since the light-emitting device of the present invention uses the light-emitting element described in Embodiment Mode 2 or Embodiment Mode 3, a light-emitting device having favorable characteristics can be obtained. Specifically, since the light-emitting element with high emission efficiency is included, a light-emitting device with reduced power consumption can be obtained.

In the above, an active matrix type image display device in which driving of a light emitting element is controlled by a transistor has been described. In addition, a passive matrix type image display in which a light emitting element is driven without providing a driving element such as a transistor. It may be a device. FIG. 4 shows a passive matrix type image display device manufactured by applying the present invention. 4A is a perspective view illustrating a passive matrix image display device, and FIG. 4B is a cross-sectional view taken along line XY in FIG. 4A. In FIG. 4, a layer 955 containing an organic compound is provided between the electrode 952 and the electrode 956 over the substrate 951. An end portion of the electrode 952 is covered with an insulating layer 953. A partition layer 954 is provided over the insulating layer 953. The side wall of the partition wall layer 954 has an inclination such that the distance between one side wall and the other side wall becomes narrower as it approaches the substrate surface. That is, the cross section in the short side direction of the partition wall layer 954 has a trapezoidal shape, and the bottom side (the side facing the insulating layer 953 in the same direction as the surface direction of the insulating layer 953) is the top side (the surface of the insulating layer 953). The direction is the same as the direction and is shorter than the side not in contact with the insulating layer 953. In this manner, by providing the partition layer 954, defects in the light-emitting element due to static electricity or the like can be prevented.

(Embodiment 5)
In Embodiment Mode 5, electronic devices of the present invention that include the light-emitting device described in Embodiment Mode 4 as a part thereof will be described. An electronic device of the present invention includes a spiro-9,9′-bifluorene derivative and a phosphorescent compound described in Embodiment 2 and has a display portion with high emission efficiency and reduced power consumption.

As an electronic device having the light emitting element of the present invention, a video camera, a digital camera, a goggle type display, a navigation system, a sound reproduction device (car audio, audio component, etc.), a computer, a game device, a portable information terminal (mobile computer, cellular phone) , Portable game machines, electronic books, etc.), an image playback device provided with a recording medium (specifically, a device provided with a display device capable of playing back a recording medium such as a digital versatile disc (DVD) and displaying the image) ) And the like. Specific examples of these electronic devices are shown in FIGS.

FIG. 5A illustrates a television device according to the present invention, which includes a housing 9101, a supporting base 9102, a display portion 9103, a speaker portion 9104, a video input terminal 9105, and the like. In this television device, the display portion 9103 is formed by arranging light-emitting elements similar to those described in Embodiments 1 to 3 in a matrix. The light-emitting element has a feature of high luminous efficiency. Since the display portion 9103 including the light-emitting elements has similar features, this television set can emit light with high luminance and consumes less power. In the television device according to the present invention, low power consumption and high image quality are achieved, so that a product suitable for the living environment can be provided.

FIG. 5B illustrates a computer according to the present invention, which includes a main body 9201, a housing 9202, a display portion 9203, a keyboard 9204, an external connection port 9205, a pointing device 9206, and the like. In this computer, the display portion 9203 includes light-emitting elements similar to those described in Embodiments 1 to 3, arranged in a matrix. The light-emitting element has a feature of high luminous efficiency. Since the display portion 9203 which includes the light-emitting elements has similar features, light emission with high luminance is possible and low power consumption is achieved. In the computer according to the present invention, low power consumption and high image quality are achieved; therefore, a product suitable for the environment can be provided.

FIG. 5C illustrates a cellular phone according to the present invention, which includes a main body 9401, a housing 9402, a display portion 9403, an audio input portion 9404, an audio output portion 9405, operation keys 9406, an external connection port 9407, an antenna 9408, and the like. . In this cellular phone, the display portion 9403 is formed by arranging light-emitting elements similar to those described in Embodiments 1 to 3 in a matrix. The light-emitting element has a feature of high luminous efficiency. Since the display portion 9403 including the light-emitting elements has similar features, light emission with high luminance is possible and low power consumption is achieved. Since the cellular phone according to the present invention has low power consumption and high image quality, a product suitable for carrying can be provided.

FIG. 5D illustrates a camera according to the present invention, which includes a main body 9501, a display portion 9502, a housing 9503, an external connection port 9504, a remote control receiving portion 9505, an image receiving portion 9506, a battery 9507, an audio input portion 9508, and operation keys 9509. , An eyepiece 9510 and the like. In this camera, the display portion 9502 is formed by arranging light-emitting elements similar to those described in Embodiments 1 to 3 in a matrix. The light-emitting element has a feature of high luminous efficiency. Since the display portion 9502 including the light-emitting elements has similar features, light emission with high luminance is possible and low power consumption is achieved. Since the camera according to the present invention achieves low power consumption and high image quality, a product suitable for carrying can be provided.

As described above, the applicable range of the light-emitting device of the present invention is so wide that the light-emitting device can be applied to electronic devices in various fields. By using the light-emitting element of the present invention, an electronic device having a display portion with high light emission efficiency and reduced power consumption can be provided.

The light-emitting device of the present invention can also be used as a lighting device. One mode of using the light-emitting element of the present invention as a lighting device will be described with reference to FIG.

FIG. 6 illustrates an example of a liquid crystal display device using the light-emitting device of the present invention as a backlight. The liquid crystal display device illustrated in FIG. 6 includes a housing 9601, a liquid crystal layer 9602, a backlight 9603, and a housing 9604, and the liquid crystal layer 9602 is connected to a driver IC 9605. The backlight 9603 uses the light-emitting device of the present invention, and current is supplied from a terminal 9606.

By using the light emitting device of the present invention as a backlight of a liquid crystal display device, a backlight with high luminous efficiency and reduced power consumption can be obtained. Further, the light-emitting device of the present invention is a surface-emitting illumination device and can have a large area, so that the backlight can have a large area and a liquid crystal display device can have a large area. Further, since the light-emitting device of the present invention is thin and has low power consumption, the display device can be thinned and the power consumption can be reduced. Further, since the light-emitting device of the present invention can emit light with high luminance, a liquid crystal display device using the light-emitting device of the present invention can also emit light with high luminance.

FIG. 7 illustrates an example in which the light-emitting device to which the present invention is applied is used as a table lamp which is a lighting device. A table lamp illustrated in FIG. 7 includes a housing 2001 and a light source 2002, and the light-emitting device of the present invention is used as the light source 2002. Since the light emitting device of the present invention has high light emission efficiency and low power consumption, the desk lamp also has high light emission efficiency and low power consumption.

FIG. 8 illustrates an example in which the light-emitting device to which the present invention is applied is used as an indoor lighting device 3001. Since the light-emitting device of the present invention can have a large area, it can be used as a large-area lighting device. In addition, since the light-emitting device of the present invention is thin and has low power consumption, it can be used as a lighting device with low thickness and low power consumption. In this manner, in the room where the light-emitting device to which the present invention is applied is used as an indoor lighting device 3001, the television set 3002 according to the present invention as described with reference to FIG. Can be appreciated. In such a case, since both devices have low power consumption, powerful images can be viewed in a bright room without worrying about electricity charges.

(Embodiment 6)
In Embodiment Mode 6, a synthesis method of a spiro-9,9′-bifluorene derivative used for the light-emitting element of the present invention will be described.

<< Synthesis Method of Spiro-9,9'-bifluorene Derivative Represented by General Formula (1) >>
The spiro-9,9′-bifluorene derivative used in the light emitting device of the present invention uses an organic compound represented by the following general formula (96) and an organic compound represented by the following general formula (97) using a metal catalyst. Can be synthesized by a coupling reaction.

(In the formula, R ¹ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ² and R ³ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. May be.)

(However, in the formula, R ⁴ represents an aryl group having 6 to 15 carbon atoms. R ⁵ and R ⁶ represent either hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, Each may be the same or different.)

First, as shown in the following synthesis scheme (a), the above general formula (96) and the above general formula (97) are heated in a suitable solvent using a metal catalyst, and expressed by the general formula (1). Spiro-9,9′-bifluorene derivatives can be obtained.

(In the formula, R ¹ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ² and R ³ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ⁴ represents an aryl group having 6 to 15 carbon atoms, R ⁵ and R ^{6 each} represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, Each may be the same or different.)

In this example, a light-emitting element of the present invention will be described with reference to FIG. The chemical formula of the material used in this example is shown below.

(Light emitting element 1)
First, indium tin oxide containing silicon oxide was formed over a glass substrate 1101 by a sputtering method, so that a first electrode 1102 was formed. The film thickness was 110 nm and the electrode area was 2 mm × 2 mm.

Next, the substrate on which the first electrode is formed is fixed to a substrate holder provided in the vacuum evaporation apparatus so that the surface on which the first electrode is formed is downward, and the pressure is reduced to about 10 ⁻⁴ Pa. After that, a layer 1103 including a composite material formed by combining an organic compound and an inorganic compound was formed over the first electrode 1102 by co-evaporation with NPB and molybdenum oxide (VI). The film thickness was 50 nm and the weight ratio of NPB and molybdenum oxide was adjusted to 4: 1 (NPB: molybdenum oxide). Note that the co-evaporation method is an evaporation method in which evaporation is performed simultaneously from a plurality of evaporation sources in one processing chamber.

Next, 2- {N- [4- (N-carbazolyl) phenyl] N-phenylamino] -spiro-9,9′-bifluorene (on the layer 1103 containing the composite material was deposited by a deposition method using resistance heating. (Abbreviation: YGASF) was formed to a thickness of 10 nm, whereby a hole-transport layer 1104 was formed.

Further, Zn (PBO) ₂ and Ir (ppy) ₂ (acac) were co-evaporated to form a light-emitting layer 1105 having a thickness of 30 nm on the hole-transport layer 1104. Here, the weight ratio of Zn _{(PBO) 2} and Ir _(ppy) 2 (acac) is _1: 0.05: adjusted such that _{(= Zn (PBO) 2 Ir} (ppy) 2 (acac)) did.

Thereafter, bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (abbreviation: BAlq) was formed to a thickness of 10 nm over the light-emitting layer 1105 by using a resistance heating vapor deposition method. Then, an electron transport layer 1106 was formed.

Further, tris (8-quinolinolato) aluminum (abbreviation: Alq) and lithium were co-evaporated on the electron transport layer 1106 to form an electron injection layer 1107 with a thickness of 20 nm. Here, the weight ratio of Alq to lithium was adjusted to be 1: 0.01 (= Alq: lithium).

Finally, a light-emitting element 1 was manufactured by forming a second electrode 1108 by depositing aluminum to a thickness of 200 nm on the electron injection layer 1107 using a resistance heating vapor deposition method. .

FIG. 10 shows current density-luminance characteristics of the light-emitting element 1. In addition, voltage-luminance characteristics are shown in FIG. Further, FIG. 12 shows luminance-current efficiency characteristics. In addition, FIG. 13 shows an emission spectrum when a current of 1 mA is passed.

(Comparative Example 1)
In Comparative Example 1, an element in which NPB is used as the hole transport layer and the other structure is the same as that of the light-emitting element 1 will be described with reference to FIG.

As shown in FIG. 9, the hole transport layer 1104 formed on the layer 1103 containing a composite material is formed by using NPB of this comparative example. That is, it was set to be the same as the light emitting element using YGASF for the hole transport layer. That is, both are the same in all layer configurations, film thicknesses, and manufacturing methods except for the material of the hole transport layer.

FIG. 14 shows current density-luminance characteristics of the light-emitting element. Further, FIG. 15 shows voltage-luminance characteristics. Further, FIG. 16 shows luminance-current efficiency characteristics. In addition, FIG. 17 shows an emission spectrum when a current of 1 mA is passed.

Table 1 summarizes the characteristics at a luminance of about 460 cd / m ² .

Thus, the light emitting device of the present invention showed very good characteristics. In addition, since the spiro-9,9'-bifluorene derivative used in the light-emitting element of the present invention has a high glass transition temperature (Tg), the light-emitting element of the present invention has excellent heat resistance. In a device having the same structure, when NPB is used for the hole transport layer and when YGASF of the present invention is used, the light emission efficiency of the device using NPB is lowered. The decrease in light emission efficiency of the device using NPB is remarkable in a device using an electron transporting host material as the host material of the light emitting layer.

A synthesis example of YGASF used in Example 1 will be described.

≪YGASF synthesis example≫
In this synthesis example, a synthesis example of YGASF will be described.

YGASF is 2-bromo-spiro-9,9′-bifluorene represented by the following structural formula (98) and 9- [4- (N-phenylamino) phenyl] carbazole represented by the following structural formula (99) ( (Abbreviation: YGA) can be synthesized by a coupling reaction using a metal catalyst.

[Step 1]
A method for synthesizing 2-bromo-spiro-9,9′-bifluorene will be described.

Magnesium was activated by putting 1.26 g (0.052 mol) of magnesium in a 100 mL three-necked flask connected with a dropping funnel and a Dim funnel, putting the system under vacuum, and heating and stirring for 30 minutes. After cooling to room temperature, the system is placed under a nitrogen stream, 5 mL of diethyl ether and a few drops of dibromoethane are added, and 11.65 g (0.050 mol) of 2-bromobiphenyl dissolved in 15 mL of diethyl ether is slowly added dropwise from a dropping funnel. After completion of the dropwise addition, the mixture was refluxed for 3 hours to obtain a Grignard reagent. 2-Bromo-9-fluorenone (11.7 g, 0.045 mol) and diethyl ether (40 mL) were placed in a 200 mL three-necked flask connected with a dropping funnel and a Dimroth. The Grignard reagent synthesized from the dropping funnel was slowly added dropwise to the reaction solution, refluxed for 2 hours after completion of the addition, and further stirred at room temperature for about 12 hours. After completion of the reaction, the solution was washed twice with saturated aqueous ammonium chloride, the aqueous layer was extracted twice with ethyl acetate, and the organic layer was washed with saturated brine. After drying over magnesium sulfate, suction filtration and concentration gave 18.76 g (yield 90%) of 9- (biphenyl-2-yl) -2-bromo-9-fluorenol solid.

A synthesis scheme (a-1) of 9- (biphenyl-2-yl) -2-bromo-9-fluorenol is shown below.

The synthesized 9- (biphenyl-2-yl) -2-bromo-9-fluorenol (18.76 g, 0.045 mol) and glacial acetic acid (100 mL) were placed in a 200 mL three-necked flask, and a few drops of concentrated hydrochloric acid were added, followed by refluxing for 2 hours. After completion of the reaction, the reaction mixture was collected by suction filtration, and washed by filtration with a saturated aqueous sodium hydrogen carbonate solution and water. When the obtained brown solid was recrystallized with ethanol, 10.24 g (yield 57%) of 2-bromo-spiro-9,9'-fluorene was obtained as a light brown powdery solid.

A synthesis scheme (a-2) of 2-bromo-spiro-9,9'-fluorene is shown below.

[Step 2]
A method for synthesizing YGA will be described.

1,4-dibromobenzene 56.3 g (0.24 mol), carbazole 31.3 g (0.18 mol), copper iodide 4.6 g (0.024 mol), potassium carbonate 66.3 g (0.48 mol) ), 18-crown-6-ether, 2.1 g (0.008 mol), placed in a 300 mL three-necked flask, purged with nitrogen, added 8 mL of DMPU, and stirred at 180 ° C. for 6 hours. The reaction mixture was cooled to room temperature, the precipitate was removed by suction filtration, and the filtrate was washed with diluted hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution and saturated brine in that order, and dried over magnesium sulfate. After drying, the reaction mixture was naturally filtered, the filtrate was concentrated, and the resulting oily substance was purified by silica gel column chromatography (hexane: ethyl acetate = 9: 1) and recrystallized from chloroform and hexane. 20.7 g (yield 35%) of N- (4-bromophenyl) carbazole was obtained as a light brown plate-like crystal.

A synthesis scheme (b-1) of N- (4-bromophenyl) carbazole is shown below.

5.4 g (17.0 mmol) of N- (4-bromophenyl) carbazole, 1.8 mL (20.0 mmol) of aniline, bis (dibenzylideneacetone) palladium (0) (abbreviation: Pd (dba) ₂ ) 100 mg (0.17 mmol) and sodium-t-butoxide (abbreviation: t-BuONa) 3.9 g (40 mmol) were placed in a 200 mL three-necked flask and purged with nitrogen, and tri-t-butylphosphine (abbreviation: P (t-Bu) ₃ ) 0.1 mL and toluene 50mL were added, and it stirred at 80 degreeC for 6 hours. The reaction mixture was filtered through Florisil (Wako Pure Chemical Industries, Ltd., catalog number: 540-00135), Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-16855), alumina, and the filtrate was washed with water and saturated sodium chloride. After washing with water, it was dried over magnesium sulfate. The reaction mixture was naturally filtered and the oil obtained by concentrating the filtrate was purified by silica gel column chromatography (hexane: ethyl acetate = 9: 1) to obtain 4.1 g (yield 73%) of YGA. .

A synthesis scheme (b-2) of YGA is shown below.

[Step 3]
A method for synthesizing YGASF will be described.

2-Bromo-spiro-9,9′-bifluorene 2.0 g (5.1 mmol), YGA 1.7 mg (5.1 mmol), bis (dibenzylideneacetone) palladium (0) 30.4 mg (0.05 mmol) t- Butoxy sodium (2.0 g, 21 mmol) was placed in a 100 mL three-necked flask and purged with nitrogen. Tri (t-butyl) phosphine (10 wt% hexane solution) 0.1 mL was added and stirred at 80 ° C. for 6 hours. After the reaction, the mixture was filtered through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-16855), and the filtrate was washed three times with water and once with a saturated saline solution and dried over magnesium sulfate. The reaction mixture was naturally filtered, and the oil obtained by concentrating the filtrate was purified by silica gel column chromatography (hexane: toluene = 7: 3). After concentration and recrystallization from chloroform and hexane, 2.9 g (yield 88%) of YGASF was obtained as a white powdery solid.

A synthesis scheme (c-1) of YGASF is shown below.

In this example, a manufacturing method of a light-emitting element different from that in Example 1 using a light-emitting layer using Zn (PBO) ₂ as a host material will be described with reference to FIGS. The chemical formula of the material used in this example is shown below.

(Light emitting element 2)
First, indium tin oxide containing silicon oxide was formed over a glass substrate 1101 by a sputtering method, so that a first electrode 1102 was formed. The film thickness was 110 nm and the electrode area was 2 mm × 2 mm.

Next, the substrate on which the first electrode is formed is fixed to a substrate holder provided in the vacuum evaporation apparatus so that the surface on which the first electrode is formed is downward, and the pressure is reduced to about 10 ⁻⁴ Pa. After that, a co-deposited film of NPB and molybdenum oxide (VI) (NPB: molybdenum oxide = 4: 1) is formed as a layer 1103 containing a composite material over the first electrode 1102 so as to have a thickness of 50 nm. A film was formed.

Subsequently, YGASF was deposited to a thickness of 10 nm as the hole transport layer 1104 over the layer 1103 containing the composite material by an evaporation method using resistance heating.

Further, a co-deposited film of YGAO11 and Ir (ppy) ₂ (acac) was formed as a light emitting layer 1105 on the hole transport layer 1104 so as to have a thickness of 30 nm using a vapor deposition method using resistance heating. The weight ratio of YGAO11 to Ir (ppy) ₂ (acac) was 1: 0.06. YGAO11 is a host material and Ir (ppy) ₂ (acac) is a dopant material.

Thereafter, BAlq was deposited as an electron transport layer 1106 on the light-emitting layer 1105 so as to have a thickness of 10 nm using an evaporation method using resistance heating.

Further, as the electron injection layer 1107, a co-deposited film of Alq ₃ and lithium was formed to a thickness of 20 nm. Alq ₃ and the weight ratio of lithium 1: was adjusted to be 0.01.

Finally, a light-emitting element 2 was completed by depositing Al with a thickness of 200 nm as the second electrode 1108 on the electron injection layer 1107 by using a resistance heating vapor deposition method.

FIG. 18 shows the current density-luminance characteristics of the light-emitting element 2, FIG. 19 shows the voltage-luminance characteristics, and FIG. 20 shows the luminance-current efficiency characteristics. Further, FIG. 21 shows an emission spectrum when a current of 1 mA is passed.

(Comparative Example 2)

In this comparative example 2, NPB was used as the hole transport layer, and the other configuration was the same as that of the light emitting element 2. The light emitting element of Comparative Example 2 will be described with reference to FIG.

As shown in FIG. 9, the hole transport layer 1104 formed on the layer 1103 containing a composite material containing a composite material is formed by using NPB of this comparative example. In addition, except having used NPB as a positive hole transport layer, it was set as the same thing as the said light emitting element 2 of this invention, ie, the light emitting element using YGASF for a positive hole transport layer. That is, both are the same in all layer configurations, film thicknesses, and manufacturing methods except for the material of the hole transport layer.

FIG. 22 shows current density-luminance characteristics of the light-emitting element. Further, FIG. 23 shows voltage-luminance characteristics. In addition, FIG. 24 shows luminance-current efficiency characteristics. In addition, FIG. 25 shows an emission spectrum when a current of 1 mA is passed.

When the current efficiency of the light emitting element of the present invention shown in FIG. 20 is compared with the current efficiency of the comparative element shown in FIG. 24, the light emitting element of the present invention shows higher current efficiency.

A synthesis example of YGAO 11 used in Example 2 will be described.

≪Synthesis example of YGAO11≫
In this synthesis example, a synthesis example of YGAO11 will be described.

Under nitrogen atmosphere, 2- (4-bromophenyl) -5-phenyl-1,3,4-oxadiazole 3.0 g (10.0 mmol), 9- (4- [N-phenylamino] phenyl) carbazole 3 .4 g (10.0 mmol), sodium t-butoxide 1.9 g (19.9 mmol) in toluene solution (45 mL), tri-t-butylphosphine (10% hexane solution) 0.3 mL, bis (dibenzylideneacetone) palladium (0) 0.3 g (0.6 mmol) was added, and the mixture was heated at 120 ° C. for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature and filtered using Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-16855), and the filtrate was washed with water and dried over magnesium sulfate. The solid obtained by filtration and concentration was dissolved in toluene, and purified by silica gel column chromatography (toluene, followed by toluene: ethyl acetate = 1: 1). Concentration and recrystallization from chloroform and hexane gave 4.7 g (yield 85%) of YGAO11 as a pale yellow solid.

A synthesis scheme (d-1) of YGAO11 is shown below.

4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 8A and 8B each illustrate an electronic device of the invention. The figure explaining the illuminating device of this invention. The figure explaining the illuminating device of this invention. The figure explaining the illuminating device of this invention. 3A and 3B illustrate a light-emitting element of an example. FIG. 6 shows current density-luminance characteristics of the light-emitting element manufactured in Example 1. FIG. 6 shows voltage-luminance characteristics of the light-emitting element manufactured in Example 1. FIG. 6 shows luminance-current efficiency characteristics of the light-emitting element manufactured in Example 1. FIG. 6 shows an emission spectrum of the light-emitting element manufactured in Example 1. FIG. 11 shows current density-luminance characteristics of the light-emitting element manufactured in Comparative Example 1. FIG. 11 shows voltage-luminance characteristics of the light-emitting element manufactured in Comparative Example 1. FIG. 11 shows luminance-current efficiency characteristics of the light-emitting element manufactured in Comparative Example 1. FIG. 11 shows an emission spectrum of the light-emitting element manufactured in Comparative Example 1. FIG. 6 shows current density-luminance characteristics of the light-emitting element manufactured in Example 2. FIG. 11 shows voltage-luminance characteristics of the light-emitting element manufactured in Example 2. FIG. 11 shows luminance-current efficiency characteristics of the light-emitting element manufactured in Example 2. FIG. 6 shows an emission spectrum of the light-emitting element manufactured in Example 2. FIG. 13 shows current density-luminance characteristics of a light-emitting element manufactured in Comparative Example 2. FIG. 11 shows voltage-luminance characteristics of the light-emitting element manufactured in Comparative Example 2. FIG. 11 shows luminance-current efficiency characteristics of the light-emitting element manufactured in Comparative Example 2. FIG. 11 shows an emission spectrum of the light-emitting element manufactured in Comparative Example 2.

Explanation of symbols

101 1st electrode 102 1st layer 103 2nd layer 104 2nd electrode 111 Hole injection layer 112 Electron transport layer 113 Electron injection layer 120 Layer 201 containing an organic compound 1st electrode 202 2nd electrode 203 Layer A containing organic compounds
204 N layer 205 P layer 206 Layer B containing an organic compound
211 hole injection layer 212 first layer 213 second layer 214 electron transport layer 215 first layer 216 second layer 217 electron transport layer 218 electron injection layer 401 drive circuit section (source side drive circuit)
402 Pixel portion 403 Drive circuit portion (gate side drive circuit)
404 Sealing substrate 405 Sealing material 407 Space 408 Lead wiring 409 FPC (flexible printed circuit)
410 Substrate 411 TFT for switching
412 TFT for current control
413 First electrode 414 Insulator 416 Layer containing organic compound 417 Second electrode 418 Light-emitting element 423 n-channel TFT
424 p-channel TFT
951 Substrate 952 Electrode 953 Insulating layer 954 Partition layer 955 Layer containing organic compound 956 Electrode 2001 Housing 2002 Light source 1101 Glass substrate 1102 First electrode 1103 Layer containing composite material 1104 Hole transport layer 1105 Light emitting layer 1106 Electron transport layer 1107 Electron injection layer 1108 Second electrode 3001 Lighting device 3002 Television apparatus 9101 Housing 9102 Support base 9103 Display unit 9104 Speaker unit 9105 Video input terminal 9201 Main body 9202 Housing 9203 Display unit 9204 Keyboard 9205 External connection port 9206 Pointing device 9401 Main body 9402 Housing 9403 Display unit 9404 Audio input unit 9405 Audio output unit 9406 Operation key 9407 External connection port 9408 Antenna 9501 Main body 9502 Display unit 9503 Housing 9 504 External connection port 9505 Remote control receiving unit 9506 Image receiving unit 9507 Battery 9508 Audio input unit 9509 Operation key 9510 Eyepiece unit 9601 Case 9602 Liquid crystal layer 9603 Backlight 9604 Case 9605 Driver IC
9606 terminal

Claims (3)

Between the anode and the cathode, a first layer containing a spiro-9,9′-bifluorene derivative represented by the following general formula (2) and a second layer containing a phosphorescent compound are included. A light emitting device characterized.

(In the formula, R ⁷ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ⁸ and R ⁹ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. R ¹⁰ represents any of an aryl group having 6 to 15 carbon atoms, and R ¹¹ and R ¹² each represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms. Each may be the same or different.) Between the anode and the cathode, a first layer containing a spiro-9,9′-bifluorene derivative represented by the following general formula (3) and a second layer containing a phosphorescent compound are included. A light emitting device characterized.

(In the formula, R ¹³ represents either hydrogen or an alkyl group having 1 to 4 carbon atoms. R ¹⁴ and R ¹⁵ represent either hydrogen or an alkyl group having 1 to 4 carbon atoms, and each is the same or different. R ¹⁶ represents an aryl group having 6 to 15 carbon atoms, R ¹⁷ represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ¹⁸ represents carbon. It represents either an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 15 carbon atoms.) 3. The light-emitting element according to claim 1 , wherein the first layer and the second layer are adjacent to each other.